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Magmatic volatile budget of the 2014 Tavurvur eruption at Rabaul volcano, Papua New Guinea

Melina Hoehn , Brendan McCormick Kilbride, Margaret Hartley

Abstract

Rabaul is a large caldera system characterised by a long and complex eruption history [1]. Rabaul's major active edifice Tavurvur places seventh overall in the world for SO2 and CO2 flux [2]. Even during inter-eruption quiescence, Rabaul was one of the highest outgassing volcanoes in PNG [3]. Since gas-rich magmas may drive violent explosive activity, reawakening of eruptions at Rabaul poses hazard and risk to thousands of people.   In this study, we investigate the pre-eruptive volatile content of magmas involved in the 2014 eruption of Tavurvur and relate these findings to the characteristics of the eruption, such as volume, gas emissions, and triggering mechanisms. We conducted analyses of 105 melt inclusions for their volatile content as well as their major and minor elements.   Volatile-trace element systematics show degassing of CO2, SO2 and H2O out of the melt. The measured volatile contents thus do not record the primary volatile contents of the Rabaul magma. We used reverse fractional crystallisation modelling together with best estimates for the primary volatile/trace element ratios to calculate the primary volatile contents of the Rabaul magma. We compare our new data with global literature data for primary arc compositions. Finally, we use our new melt inclusion data to calculate the amount of SO2 released during the 2014 eruption and compare our findings with satellite-derived observations.   [1] Patia H et al. (2017) J Volcanol Geotherm Res 345:200-217 [2] Aiuppa A et al. (2019) Sci Rep 9:5442 [3] Carn S et al. (2017) Sci Rep 7:44095